Values Of Parameters Research Articles

A new hybrid parallel genetic algorithm for multi-destination path planning problem

This paper proposes a new parallel approach of multi objective genetic algorithm for path planning problem. The main contribution of this work is to reduce the population size that effect in decreasing processing times of finding the optimum path for multi destination problem. This is achieved by combining the local population of island parallel approach and global population of global parallel approach. Various experiments have been conducted to evaluate the new hybrid parallel genetic algorithm (HPGA) in solving multi-objective path planning problems. Three different test areas with 2 destinations were used to assess the performance of HPGA. Furthermore, this work compares HPGA and sequential genetic algorithm (SeqGA), as well as compared to other existing parallel genetic algorithm (GA) methods. From experimental results show that proposed HPGA outperform others, in term of processing time i.e., up to 3.6 times speedup faster, and lowest GA parameter values. This proposed HPGA can be utilized to design robots with fast and consistent path planning, especially with various obstecles.

Ultrasonic evaluation MAFLD in screening severety matabolic disorders

Metabolic dysfunction associated fatty liver disease (MAFLD) is a new proposed term for non-alcoholic fatty liver disease (NAFLD). a liver steatosis associated with Type 2 diabetes mellitus or increased physical weight/thickness, or with two or more metabolic disorders. This indicates metabolic abnormalities that result in fat accumulation in hepatocytes without the presence of alcoholic liver disease or other causes that would lead to hepatocyte abnormalities. Our goal was determine the correlation between certain stages of fatty liver disease determined by ultrasonography with increased body weight/obesity, diabetes mellitus and other metabolic disorders and with the values of biochemical parameters of liver enzymes. A prospective study was conducted at the public health institution Zivinice Health Center from August 2022 until January 2024 on a random sample of 101 patients. Observing the entire examined group, a difference in the gender distribution of hepatic steatosis is noticed, and graphically it is shown that men have hepatic steatosis more often than women. In fatty liver disease (MAFLD), stage G2 was most prevalent in 32% of patients. Ultrasonography, along with clinical and biochemical indicators, should be an integral part of screening and monitoring of metabolic disorders as it is a non-invasive and easily accessible imaging method and allows timely therapeutic action and prevention of hepatic and extrahepatic complications.

Combinative distance-based assessment method using linguistic T-spherical fuzzy aggregation operators and its application to multi-attribute group decision-making

Clean energy has become a hot topic worldwide because of the continuous rise in the climate's temperature. Reduced air pollution is only one of the many economic and environmental advantages of clean energy. An effective contractor with experience and knowledge in clean energy projects is always required to handle the complicated process of planning, implementing, and maintaining the new clean energy infrastructure. Contractor selection for renewable energy projects (REPs) is a multi-attribute group decision-making (MAGDM) problem. Linguistic T-spherical fuzzy set (LT-SFS) can be compatible with fuzzier information, and the contractor selection problem also has a lot of fuzzy information, which makes LT-SFS very suitable for contractor selection for REPs. Hence, the present work proposes a MAGDM methodology utilizing a combinative distance-based assessment (CODAS) method within the LT-SF context. For that, the Einstein and Frank t-norm and t-conorm has been used to define new and generalized operational laws for linguistic T-spherical fuzzy numbers. Then, the linguistic T-spherical fuzzy Einstein and linguistic T-spherical fuzzy Frank aggregation operators are proposed to integrate the information data provided by experts. Moreover, the proposed aggregation operators based-CODAS approach is designed to evaluate and rank the available alternatives. A real-life decision problem of selecting the best suitable contractor for a renewable energy project is solved to verify our suggested technique. Moreover, the sensitivity analysis is also carried out by changing the parameter's value to check the consistency of the rank order. Finally, the new model is compared with existing approaches to demonstrate its strength. The comparative analysis shows that the results of the suggested technique are more feasible and beneficial than those of existing approaches.

Analysis of Current-Voltage Properties of Al/p-si Schottky Diode with Aluminium Oxide Layer

In our study, the effects of the metal oxide (aluminum oxide, Al2O3) thin film placed between the metal and the semiconductor on the diode's characteristics were investigated. The Al2O3 thin film was suitable for its growth on a p-type silicon substrate by the atomic layer deposition (ALD) technique. In this study, a diode structure with an oxide interlayer was fabricated. To investigate the electrical parameters of the fabricated Schottky diode, measurements of current-voltage (I-V) were carried out at room temperature and in the 5 V voltage range. Using the I-V measurements, diode parameters such as the barrier height (Φb), the ideality factor (n), and the current density (I0) were evaluated using the theory of thermionic emission (TE) and Cheung's method. Using the TE method and Cheung’s method, the approximate values of Φb, n parameters were calculated as 0.77 eV, 5.43, and 0.77 Ev, 5.97, respectively. According to calculations, the developed Schottky diode is a rectifier diode and has been determined to have photodiode properties. This research offers an understanding of the production and electrical characteristics of Schottky devices based on Al2O3.

Hybrid uncertainty approach for management of energy storage-embedded soft open points in distribution grids

Energy storage-embedded soft open point (ESOP) is an innovative electronic device that incorporates energy storage capabilities and is designed to interconnect two or three neighboring distribution feeders. Its primary functions include active power control, reactive power compensation, and grid voltage regulation. On the other hand, distribution grids have been equipped with other distributed energy resources (DERs) such as smart PV inverters, renewable energy sources (solar and wind), and so on. Therefore, this article proposes a novel management scheme for the mentioned devices in distribution grids based on a convex formulation to take powerful solvers like CPLEX into account. Since there are a set of uncertainties associated with the model, including renewable resources, loads, and market price, a hybrid framework is developed based on the unscented transformation (UT) method and information gap decision theory (IGDT). In other words, the uncertainties of renewable resources and loads are captured by the UT method which could provide a correlation among uncertain parameters, while the IGDT method is employed to model the uncertainty associated with the market price. The hybridization of these methods assists in reducing the discrepancy between the actual and predicted values of uncertain parameters. The model is applied to a 33-bus grid, considering various case studies. The proposed method results in a substantial operational cost reduction of approximately 26.82 %. Additionally, it ensures a flatter voltage profile across the network, with the minimum voltage reaching 0.985 p.u.

The Allen–Cahn model with a time-dependent parameter for motion by mean curvature up to the singularity

In this article, we investigate the temporal evolution of arbitrary, simple, closed two-dimensional (2D) and three-dimensional (3D) interfaces under motion driven by mean curvature up to a singularity. To facilitate this investigation, we propose a novel Allen–Cahn (AC) model with a time-dependent interfacial thickness parameter. The original AC equation was developed to model the phase separation of a binary mixture. It is well known that a level set or interface of the solution of the AC equation obeys the dynamics of motion by curvature as the interfacial thickness parameter approaches zero. Generally, it is difficult to find a closed-form analytic solution of the AC equation with any initial condition. Therefore, we need to estimate the solution of the AC equation through computational approaches such as finite difference method (FDM), finite element method (FEM), Fourier-spectral method (FSM), and finite volume method (FVM). Any simple, closed curves and convex surfaces eventually shrink to a point due to motion by mean curvature. Therefore, it becomes necessary to use adaptive mesh techniques to resolve this small size problem. However, even though we use adaptive mesh techniques, we still confront the relatively thick interfacial transition layer when the curves or interfaces become very small. To avoid this problem, we can start with a very small mesh size for a small value of the interfacial parameter, which results in an extremely high computational cost even when using adaptive mesh techniques. To resolve these issues, we present the AC equation with a time-dependent interfacial parameter and develop an adaptive mesh refinement system. To show the superior performance of the proposed mathematical equation and its computational algorithm, we present various numerical experiments and investigate the motion by mean curvature up to the singularity of curves in 2D space and interfaces in 3D space.

The effect of increased listening effort on the balance performance of patients with compensated vestibular lesion

ObjectivesThis study investigated the effects of listening effort (LE) on balance in patients with compensated vestibular deficits compared to healthy peers. MethodsThe subjects included two main groups: a control group of 15 healthy subjects and a study group of 19 patients with compensated vestibular pathology. The computerized dynamic posturography test (CDP) was conducted without the speech-in-noise task as a baseline, then the participant was subjected to a dual task in which the auditory task (speech-in-noise sentences) was given as the primary task, and the balance function test was the secondary task. Results: within-group analysisThe study group showed statistically significantly worse values of all body balance parameters under dual-task than the baseline in all conditions. These differences were much higher under the compliant platform conditions. However, these findings were not statistically significant in the control group. Between-group analysisThe study group showed a statistically significant decline in body balance reactions compared to the control group under dual-task with increased listening effort and the compliant platform. Study subgroup analysis revealed statistically significant differences between patients with unilateral vestibular loss (UVL) and those with bilateral vestibular loss (BVL) in the unstable platform condition. ConclusionOur study regarding implementing a dual-tasking paradigm as a measure of LE during the evaluation of chronic vestibular patients with CDP demonstrated how dual-tasking with increased LE affects postural stability. Because of this, patients will probably be more prone to tripping and falling in multitasking situations, as found in real-world settings. This fact should be taken into consideration while testing patients with chronic vertigo and compensated states at VNG. A dual-task paradigm helps uncover the unrevealed pathology.

Soret and Dufour effects on two dimensional steady MHD flow past a semi‐infinite vertical porous plate in the presence of thermal radiation and radiation heat absorption with constant heat and mass flux

AbstractThe problem of a two‐dimensional steady, MHD convective, incompressible, viscous flow past a uniformly moving semi‐infinite vertical porous plate embedded in a porous medium in the presence of radiation heat absorption, thermal radiation, thermal diffusion, and diffusion thermo effects with constant heat and mass flux are studied. In the fluid region, a transversely oriented, homogeneous magnetic field of intensity is applied. The non‐dimensional governing equations are solved analytically adopting asymptotic series expansion method. The impacts of several physical quantities including Grashof number, Schmidt number, Prandtl number, Soret number, radiation absorption, radiation parameter, magnetic field within the flow domain and transport characteristic have been explored graphically. It has been found that fluid velocity and skin friction fall with enhancing the values of magnetic parameter. Further, temperature and concentration fields rise with an increase in the Soret effect.

Uncertainty assessment of aquifer hydraulic parameters from pumping test data

Data from pumping tests is a noisy process, and therefore, performing the pumping test numerous times will not get the same drawdown values. As a consequence, various pumping experiments lead to different values for aquifer parameter estimates. The data of pumping tests are usually analyzed using traditional methods (aquifer tests and AQtesolv software), which depend on trial and error technique. During these methods, non-unique values of hydraulic parameters are selected, which usually have a high level of uncertainty. Uncertainty must be taken into account in determining aquifer parameters, especially when using groundwater models for decision makers. The main goal of this study is to build a comprehensive tool for quantifying uncertainty associated with hydraulic parameter estimation from different pumping test conditions for fully penetrating wells in confined and semi-confined aquifers. To achieve the previous objective, a FORTRAN code was developed to apply the Markov Chain Monte Carlo (MCMC) algorithm using different likelihood functions (exponential, inverse, and log). This developed tool can be used to detect the most probable range of aquifer parameters that are consistent with pumping test data with a high degree of confidence. The tool was successfully used to several hypothetical cases to demonstrate the uncertainty in the quantification of aquifer parameters and compare the findings to the standard method's results. Also, the concept was verified numerically (using Modflow program) with satisfactory results using a hypothetical case with well-known aquifer parameters. Finally, the tool was applied for actual pumping test data with good results.

Research on NURBS Curve Interpolation Algorithm Based on Mline-Gear

Aiming at the problem of speed fluctuation caused by the large error between the ideal interpolation step and the actual interpolation step in the traditional non-uniform rational B-spline ( NURBS ) curve interpolation, a NURBS curve interpolation algorithm based on Mline-Gear is proposed. The differential and derivative definitions are derived to transform the Mline and Gear formulas respectively, and the prediction and correction formulas of the interpolation parameters are obtained. Then, it is judged whether the interpolation parameter values obtained by the correction formula meet the speed fluctuation rate requirements, and the interpolation can be continued. Otherwise, the Steffensen descent formula is used to iteratively correct the interpolation parameter values. In order to ensure the calculation accuracy and avoid solving high-order derivatives, the fourth-order Runge-Kutta method is used to solve the initial two interpolation parameters. Finally, the algorithm is simulated. The simulation results show that the algorithm reduces the feed speed fluctuation rate while ensuring a small number of iterations.

Mathematical Formulation of a Co-infection Model and its Analyses for Monkeypox and HIV/AIDS Infections

The dynamics of the co-infection of monkeypox and HIV/AIDS is examined from a mathematical perspective via a deterministic 13-compartment model. This consists of the investigation of the equilibrium points, the basic reproduction numbers and the equilibrium points’ stability. The mathematical analysis reveals that the model is epidemiologically well-posed, and that the basic reproduction number for the monkeypox sub-model is a function of the likelihood of getting infected, the rate of effective contact, the infection coefficient of the monkeypox-infectious class, the monkeypox prevention measure, the progression rate from monkeypox-exposed class to monkeypox-infectious class, the natural death rate, the vaccination rate and the waning rate of the vaccine. It also depends on the recovery rate for the monkeypox-exposed class and the monkeypox-induced death rate. The analysis also reveals that the basic reproduction number for the HIV/AIDS sub-model is a function of the likelihood of getting infected, the rate of effective contact, the HIV/AIDS prevention measure, the infection coefficient of the monkeypox-infectious class, the HIV/AIDS-induced death rate, the natural death rate, the infection coefficient of AIDS-only class, and the progression rate of HIV-only class to AIDS-only. The stability analysis reveals that the disease-free equilibrium of the sub-models are globally asymptomatically stable, when the basic reproduction number is less than unity. Numerical simulations of the model reveal the effect of changes in certain parameter values on the population sizes. Increasing or lowering the values of certain parameters can significantly affect the sizes of some classes. The Maple 18 programming software was used to carry out all calculations and numerical simulations.

A non‐similar solution to dissipative Eyring‐Powell nanofluid flow over a nonlinear stretching surface with an inclined magnetic field and active/passive nanoparticles flux

AbstractAmongst numerous non‐Newtonian fluid models, Eyring‐Powell fluid is prominent owing to its shear thinning, pseudoplastic, and yield stress unique characteristics. It has varied industrial applications including the modeling of polymer melts, food products, and blood flow. This study discusses the Darcy Forchheimer flow of Eyring‐Powell nanoliquid along a nonlinear stretched surface influenced by an inclined magnetic flux. The mass and heat transmissions are supported by active and passive control of nanoparticles respectively. The unique effect of viscous dissipation is introduced to influence the liquid velocity and temperature. Unlike the majority of the research being published that espouses similar solutions, we adopted the non‐similar analysis of the proposed problem to eradicate the chance of the variable in the parameters. This was a challenging task and was taken as a mathematical art rather than a science. The established Buongiorno model is followed to compute the thermophoretic and Brownian motion effects. The numerical computation of this mathematical system is performed using the bvp4c algorithm. The results are described through graphs and in numerically calculated tabulated values. It is determined that wall drag is stronger when the magnetic field is inclined at an angle of than at . Additionally, it is observed that passive control of nanoparticles results in better rates of heat and mass transmissions, against varied values of the fluid parameter with . The validation of the envisioned model is also a part of this exploration.

Multigrid simulations of non-Newtonian fluid flow and heat transfer in a ventilated square cavity with mixed convection and baffles

The impact of baffles on a convective heat transfer of a non-Newtonian fluid is experimentally studied within a square cavity. The non-Newtonian fluid is pumped into the cavity through the inlet and subsequently departs from the cavity via the outlet. Given the inherent non-linearity of the model, a numerical technique has been selected as the method for obtaining the outcomes. Primarily, the governing equations within the two-dimensional domain have been discretized using the finite element method. For approximating velocity and pressure, we have employed the reliable P2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathbb{P}}_{2}$$\\end{document}–P1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\mathbb{P}}_{1}$$\\end{document} finite element pair, while for temperature, we have opted for the quadratic basis. To enhance convergence speed and accuracy, we employ the powerful multigrid approach. This study investigates how key parameters like Richardson number (Ri), Reynolds number (Re), and baffle gap bg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\ ext{b}}}_{{\ ext{g}}}$$\\end{document} influence heat transfer within a cavity comprising a non-Newtonian fluid. The baffle gap (bg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${b}_{g}$$\\end{document}) has been systematically altered within the range of 0.2–0.6, and for this research, three distinct power law indices have been selected namely: 0.5, 1.0, and 1.5. The primary outcomes of the investigation are illustrated through velocity profiles, streamlines, and isotherm visualizations. Furthermore, the study includes the computation of the Nuavg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${Nu}_{avg}$$\\end{document}(average Nusselt number) across a range of parameter values. As the Richardson number (Ri) increases, Nuavg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${Nu}_{avg}$$\\end{document} also rises, indicating that an increase in Ri results in augmented average heat transfer. Making the space between the baffles wider makes heat flow more intense. This, in turn, heats up more fluid within the cavity.

Uncertainty in the dynamic properties of tall buildings and propagation to the wind‐induced response

SummaryThe response of tall buildings to wind actions is commonly assessed through the quasi‐static approach considering mean, background, and resonant components of the action. The latter accounts for the amplification due to resonance and depends on the dynamic properties of the buildings, that is, modal mass, frequency, and damping ratio. Selecting appropriate values of the modal parameters of tall buildings is not immediate and is usually done using predictive models. These contain uncertainty, which eventually propagates to the dynamic response. The main aim of the paper is the assessment of uncertainty in the dynamic response of flexible buildings to wind action arising from a not perfect knowledge of their dynamic properties. The paper explicitly refers to the dynamic models given by Eurocode 1, but the approach is general, and the analyses can be repeated selecting any other model. It is found that the bias in the dynamic factor is always less than one, with values on average between 0.86 and 0.98. This indicates that the approach of Eurocode 1 is conservative. The only exception is that of the acrosswind response of steel buildings with an high aspect ratio, in which case the bias can be as large as 1.16. As to randomness, the coefficient of variation of the alongwind dynamic factor is very seldom found to exceed 10%, with average values around 5%. Such values are much lower than those of the coefficient of variation of damping, which is in the order of 50% or more. This indicates that uncertainty attenuates when it propagates to the response. On the other hand, the coefficient of variation of the acrosswind and torsional dynamic factors reaches values of 20% or more, indicating that such attenuation is much lower in that case.

Estimating the slip rate in the North Tabriz Fault using focal mechanism data and GPS velocity field

Abstract This study delves into slip distribution on the North Tabriz Fault (NTF), a critical aspect of seismic hazard analysis due to its proximity to the Tabriz metropolis. The study operates within a uniform elastic half-space, maintaining constant values for fault geometry and regional rheological parameters throughout the research. To calculate strain boundary conditions, permanent and periodic global positioning system (GPS) data from the northwest region were utilized. The fault was constrained perpendicularly while allowing tangential movement, facilitating the determination of its annual slip rate using the boundary element method, with the Okada analytical model serving as the fundamental solution. The findings underscore the intricate relationship between the fault’s slip rate and boundary conditions, revealing a predominant right-lateral strike-slip motion. The study offers two slip rate assessments, obtained through earthquake focal mechanisms and GPS velocity data, yielding values of 5 and 5.5 mm / year {\rm{mm}}/{\rm{year}} , respectively. Importantly, the alignment of these calculated slip rates with paleo-seismological data underscores the credibility of the results generated via the boundary element method, distinguishing it as a reliable approach when compared to other numerical and analytical techniques. This research provides valuable insights into the behavior and slip dynamics of the NTF, which is pivotal for assessing seismic risks.

A Critical Review on Room-Temperature Sodium-Sulfur Batteries: From Research Advances to Practical Perspectives.

Room-temperature sodium-sulfur (RT-Na/S) batteries are promising alternatives for next-generation energy storage systems with high energy density and high power density. However, some notorious issues are hampering the practical application of RT-Na/S batteries. Besides, the working mechanism of RT-Na/S batteries under practical conditions such as high sulfur loading, lean electrolyte, and low capacity ratio between the negative and positive electrode (N/P ratio), is of essential importance for practical applications, yet the significance of these parameters has long been disregarded. Herein, it is comprehensively reviewed recent advances on Na metal anode, S cathode, electrolyte, and separator engineering for RT-Na/S batteries. The discrepancies between laboratory research and practical conditions are elaborately discussed, endeavors toward practical applications are highlighted, and suggestions for the practical values of the crucial parameters are rationally proposed. Furthermore, an empirical equation to estimate the actual energy density of RT-Na/S pouch cells under practical conditions is rationally proposed for the first time, making it possible to evaluate the gravimetric energy density of the cells under practical conditions. This review aims to reemphasize the vital importance of the crucial parameters for RT-Na/S batteries to bridge the gaps between laboratory research and practical applications.

Mathematical model of the topological structure of the urban water supply network

To effectively manage urban water supply networks, utility companies providing water supply and drainage (hereinafter referred to as KP "Vodokanal") need to solve the following problems: - use of topographic maps of scales 1:500, 1:1000, 1:2000, which include both ground-based buildings , as well as adjacent underground communications - water supply and sewerage, electrical networks, gas supply networks, heat supply, communications, etc.; - hydraulic calculations of the water supply network to determine the condition, analysis and optimization of the network structure; - prompt elimination of emergency situations and re-sumption of the network after the emergency is eliminated; - control and management of drinking water quality; - availability of pressure, flow and piezometer monitoring devices; - automated control of pumping stations; - saving energy resources; – network inventory. A comprehensive solution to these problems is provided by a geoinformation automated water supply network management system. Automated network management is carried out using geoinformation technologies, mathematical and geoinformation models of the water supply network. The work proposes a mathematical model of the topological structure of the water supply network, defines geospatial data bases about network objects and the interrelation-ships of these objects, taking into account the topological structure of the network to provide geoinformation and mathematical modeling of the hydraulic state of the water supply net-work, solving problems of emergency processing, monitoring the quality of drinking water, and optimizing the network, energy saving. To construct a digital model of the branched-ring structure of a topological graph, digital vector topographic maps are used as follows: - based on the results of geodetic surveys, water supply network facilities are marked on the topog-raphic map with symbols; - analysis of information-graphic diagrams of well details indicates the presence of pressure/flow regulators and hydrants. If there are regulators, their symbols are applied to the polyline of the water supply section at the symbol of the well at the point where the water pipe is inserted into the well, their diameters and the percentage of opening are indicated; - if there is a hydrant, the symbol for a well without a hydrant is replaced with the symbol for a well with a hydrant; - for all objects of the water supply network, the values of technical and graphic parameters are determined; - the orientation of the graph is deter-mined - the direction of water flow; – a matrix of incidents of vertices and contours is formed.

Bulk viscous late acceleration under near equilibrium conditions in f(R, T) gravity with mixed dark matter

Numerous studies have tried to explain the observed late acceleration of the Universe as being caused by the bulk viscosity associated with the dark matter (DM) component. However, for driving the said accelerated expansion, all such models require a violation of near equilibrium conditions (NECs) associated with the background viscous theory. But recently, it was found that, with the aid of a cosmological constant, it is possible to maintain NEC for the bulk viscous warm DM during certain evolutionary epochs of the Universe. Nevertheless, this negated the possibility of having a ‘solely’ viscous-driven late acceleration in Einstein gravity within the NEC limit. In the present study, we investigate a model of the Universe composed of mixed DM components, with viscous DM, and inviscid cold DM as its constituents, in the context of R+2λTvm gravity, and show that the model predicts late acceleration by satisfying NEC, critical energy condition and second law of thermodynamics (SLT) throughout the evolution, even in the absence of a cosmological constant. One intriguing feature observed in this model is the possibility of having a negative bulk viscous coefficient and yet satisfying the SLT. Finally, by applying both theoretical and observational constraints on the model parameters, we determined the best-fit values of model parameters and thereby analyzed the evolutionary behavior of some relevant cosmological observables.

Qualitative Behavior for a Discretized Conformable Fractional-Order Lotka-Volterra Model With Harvesting Effects

The predator-prey model is a widely mathematical structure that explains the dynamics between two interacting populations: predators and prey. The predator-prey interaction represents a fundamental dynamic in nature, influencing the stability and balance of ecosystems worldwide. The purpose of this article is to provide insight into the complex interactions and feedback mechanisms between predators and prey in ecological systems via mathematical tools such as stability and bifurcation. We investigate a fractional-order Lotka-Volterra model with a harvesting effect using stability and bifurcation theory. The equilibrium points and local stability of the purposed model are presented in this article. The bifurcation analysis, which is a potent approach used to analyse the qualitative behavior of the predator-prey system as the parameter values are varied, is also explored. In particular, a Neimark-Sacker bifurcation and a period-doubling bifurcation are theoretically and numerically examined. Furthermore, we illustrate some 2D figures to show the phase portriat and bifurcations of this model at various points.

Nonisothermal analysis of two uniform boundary layer shear flows

AbstractThe heat transfer phenomenon on the multiphase flows plays an imperative role in several biological and industrial processes, like the oil production industries, catalytic reactors, energy losses in several thermal systems, energy storage, paper manufacture, and heat exchanger systems. Therefore, this study scrutinized the heat transfer characteristic between two uniform boundary layer shear flows with different strengths flowing in the same direction. This problem involves the simulation of the convergence of boundary layers with varying shear strengths. The nonlinear differential system is scrutinized and converted into dimensionless ordinary differential equations by employing appropriate dimensionless variables. The resulting set of highly nonlinear ordinary differential equations is resolved numerically utilizing the Matlab solver “bvp4c.” The resulting numerical solutions are used to construct graphs that illustrate and elucidate the impact of numerous physical parameters on flow patterns. For both fluids, results for the Nusselt number and shear stress are also presented graphically for various parameters. The acquired results demonstrate that the velocity profile upsurges for both upper and lower fluids by enhancing the shear parameter. Furthermore, the number of streamlines is enhanced by augmenting the values of the viscosities ratio parameter. The present problem applies to the trailing edge flow over a thin airfoil with camber.